1. Field of the Invention
The present invention relates generally to poster frames and display holders for various types of replaceable posters, pictures and similar advertising materials. More specifically, the invention pertains to an anti-theft or tamper-proof poster display device which can be used in many various areas, such as on buses, taxi cabs, and similar mobile installations, as well as on fixed mounts such as on posts or walls in service stations, subway terminals, movie theaters or the like. The poster display device is neat, trim, aesthetic, and capable of being used either indoors or outdoors. It is particularly useful in applications where theft of the poster, picture or advertising material could be a problem.
2. Description of the Prior Art
Tamper proof poster display devices of the prior art have typically been constructed in the form of a locked box containing the poster, having a window through which the poster could be viewed. Such devices are typically expensive and require key operated locks. Many of such glass boxes also need internal fluorescent lighting since the box construction could cast shadows on the poster. These prior art poster display devices are also cumbersome and unattractive, and expensive to repair or replace.
In contrast to the cumbersome window box or showcase style poster display device, a variety of more streamlined and economical spring loaded poster display devices have been developed by the assignee of the present invention. However, until the present invention, the spring loaded poster display devices have been operable and changeable by hand and have not been entirely tamper-proof.
As well as being an improvement over the window box or show case style devices, the present invention is an improvement over the invention disclosed and claimed in U.S. Pat. No. 4,145,828 and assigned to the assignee of the present invention. In that patent a display holder is set forth having a plurality of frame sections. Each of the sections is made essentially of two extruded portions which are pivoted together, the extruded portions being of any material which can be economically extruded, such as aluminum. Extruded frame sections are biased by means of an unbent metal leaf spring which coacts with the two extruded portions to releaseably clamp posters or similar display items in the frame. The invention as disclosed and claimed in U.S. Pat. No. 4,145,828 was itself an improvement over U.S. Pat. No. 3,310,901 which employed cantilever action-type metal leaf springs with S-shaped hooks at one end to bias together the two parts of the frame.
The present invention is also an improvement over the inventions disclosed in the following patent applications: Ser. No. 424,883, filed Sept. 27, 1982, entitled "Spring Loaded Poster Frame"; Ser. No. 448,047, filed Dec. 8, 1982, entitled "Spring Loaded Poster Frame"; and Ser. No. 499,441, filed June 6, 1983, entitled "Improved Spring Loaded Poster Frame". Each of the foregoing patent applications are assigned to the assignee of the present invention. Generally the inventions disclosed and claimed in these applications relate to plastic poster frame and display holders including a relatively resilient elongated plastic portion which is integrally formed as part of the poster frame sections for providing biasing forces or clamping forces for holding the poster or display material between hingedly connected extruded frame forming sections.
While each of the aforesaid inventions has proven generally suitable, none are completely tamper-proof. Generally speaking, each of the display holders includes means attached to or formed on the outwardly facing extruded portion for grasping in manipulation to open or close the outwardly facing portion relative to the other extruded portion. Typically such grasping means takes the form of a formed side panel or flange having a ridge thereon or otherwise defining a longitudinal recess which can be grasped in manipulation to open or close the frame. Each of these poster frame devices can be readily opened and hence can be tampered with by vandals or by simply curious bypassers. Since often times posters, pictures, or advertising material must be displayed in places such as movie theaters, subway terminals, bus terminals, or airport terminals where idle, unsupervised crowds will congregate, there is a great need for an economical and aesthetically pleasing tamper-proof poster frame.